Printed circuit board (PCB), integrated circuit (IC) and integrated circuit package substrate (IC package) design is becoming increasingly complex due to a variety of factors. Such factors include increasing data rates of signals conveyed by PCBs, increasing numbers of I/O circuits disposed in an IC, decreasing sizes of circuits, increased density of circuits in PCBs, ICs and IC Packages, numerous layers in the PCBs, and increased PCB thickness. Many of these factors lead to increased density of connectors, such as vias, pins and traces, within and between PCBs, ICs and IC Packages.
As the density and signal rates of PCB, IC and IC Package elements increase, elements of the PCBs, ICs and IC Packages experience increased crosstalk. Generally, crosstalk can occur when signals being routed by neighboring circuit elements interfere with each other. Crosstalk can lead to increased signal noise, which in turn, can make it more difficult for a receiver to correctly interpret a signal or for other circuits on the IC to perform their desired functions.
Previous attempts to limit crosstalk have relied on isolating neighboring elements from each other through physical separation, or through the use of virtual grounding planes. As the density of elements on PCBs, ICs and IC Packages increases, it becomes more difficult to prevent crosstalk through these mechanisms.